[Significance of abnormally high somatosensory evoked potentials (SEV)]

Data found in the literature and our own observations prompted us to consider the possibility that abnormally enlarged Somatosensory Evoked Potentials (SEPs) may have a diagnostic and physiopathological significance, particularly in a group of diseases which include common clinical features of encephalopathy with stimuli-sensitive myoclonus and epilepsy, whatever their etiology may be (degenerative or storage disease, metabolic, toxic or post-hypoxic encephalopathy...). We discuss the amplitude, morphology, diagnostic and therapeutic contribution of these 'giant' SEPs and pathogenic assumptions with reference to 'cortical reflex myoclonus'. Studies of back-averaged encephalogram, SEPs and long-loop reflexes allow some illustration of a functional hyperreactivity of the sensori-motor cortex, but no conclusive demonstration of its origin.